This invention relates generally to the design and development of spacecraft and, more particularly, to a modular approach to the design of spacecraft, such as earth-orbiting satellites. Traditionally, each spacecraft is considered unique to its intended purpose or mission. In general, a spacecraft includes a combination of complex subsystems, for performing such functions as propulsion, communications, power generation and storage, attitude control, and thermal control. Each subsystem has different requirements and specific functions, depending on the spacecraft mission. Even a simple spacecraft may have subsystems with hundreds of components that have to be uniquely interconnected and controlled to perform as required.
Most spacecraft today are extremely expensive, heavy, and make inefficient use of volume because of the way spacecraft subsystems are designed and housed. Traditionally, spacecraft are box-like structures, which use the space inside a launch vehicle fairing very inefficiently. Avionics and payload equipment are housed in large boxes attached to the spacecraft. Moreover, the avionics components within each box are typically arranged along the inside walls of the box, which is, therefore, largely empty. Payloads today necessarily include large solar arrays and antennas, which have to be accommodated between the spacecraft box structure and the curved fairing of the launch vehicle, or entirely above the spacecraft structure. Current avionics accommodation approaches are relatively heavy because it is partitioned into many different units connected by heavy wiring harnesses and waveguides. Large equipment panels typically incorporate heavy thermal conducting material, adding more weight, and the panels must often be stiffened to remedy for acoustic vibration problems that the panels encounter during launch.
Some designers have introduced the concept of a standard spacecraft "bus," the intended purpose of which is to provide an "standard" vehicle for different space missions. However, such so-called standard buses often need many customizing modifications from one mission to the next. Even identical units used on the same spacecraft often require individual analysis, accommodation and documentation due to varying placement, orientation and accommodation within a spacecraft. Some initial progress has been made in reducing design cost by using standardized connector hardware and data buses for transmission of data between components or subsystems. Even with these standardized features, however, the spacecraft design process still requires an extremely costly design effort and a rigorous and detailed system integration and testing phase. Moreover, the resulting vehicle is still inefficient in terms of its weight and use of volume.
Ideally, a new spacecraft architecture is needed, to provide a more compact and lighter spacecraft, which can be designed, manufactured and tested more quickly, and which facilitates increased reuse of existing designs, but without limiting mission flexibility. As will shortly become apparent from the description that follows, the present invention meets and exceeds these goals.